This invention relates in general to a pump, and more particularly to a steam driven pump for draining fluid from a container.
Pump assemblies with over-center snap-action mechanisms are useful in controlling the filling of a closed or sealed pressure vessel. For example, U.S. Pat. No. 6,099,260 to Francart, Jr. discloses a pressure vessel having a poppet type vent valve for venting the interior of the vessel to the surrounding atmosphere, a plurality of gas inlet valves subjected to high pressure inlet fluid, and a plurality of compression springs. During filling of the pressure vessel, the vent valve is in the open position and the pressure valves are closed by a float operated over-center snap-action valve actuating mechanism. As the vessel fills with fluid, the float rises and a rotatable float arm, forming part of the valve actuating mechanism, is rotated about a pivot point at one end, causing an over-center toggle linkage mechanism to move toward the center position against a spring bias. Such a mechanism has toggle linkage elements which snap quickly through the center position, closing the vent valve while simultaneously snap opening the plurality of high pressure inlet valves to pump the accumulated liquid from the vessel. Typically a compression coil spring provides such a biasing force with one end of the coil spring coupled to a fixed or stationary member of the valve mechanism or vessel.
While such over-center snap-action valve mechanisms operate satisfactorily to automatically control the liquid inflow and outflow from the pressure vessel, such known mechanisms are complex, difficult to maintain, and expensive. Further, the biasing force is always present as the float rises and lowers within the vessel, and the float must be sufficiently buoyant to overcome the large spring force or spring rate of the plurality of compression springs.
It would therefore be advantageous to provide a pump that is reliable, has a simple design, and easy to maintain and repair. It would further be advantageous to provide a pump in which the float is connected to the valve actuating mechanism and is not biased by a spring during its entire range of pivotal travel.
The above objects as well as other objects not specifically enumerated are achieved by a pump including a valve mechanism having an opened position and a closed position. The pump further includes a spring assisted mechanism for selectively moving the valve mechanism between the opened position and the closed position, and a fluid detector for detecting the level of a pumping fluid. The fluid detector is pivotally connected to the spring assisted mechanism and has a first range of pivotal travel and a second range of pivotal travel. The fluid detector further engages a spring of the spring assisted mechanism only at one portion of the first range of pivotal travel, and engages the spring of the spring assisted mechanism only at one portion of the second range of pivotal travel. The fluid detector is disengaged from the spring of the spring assisted mechanism at all other portions of the first range of pivotal travel and of the second range of pivotal travel.
In another embodiment of the invention, the pump includes a container and a valve block mounted to the container. The valve block has a body, a pressurized fluid inlet valve, and a pressure release valve. The valve block is further readily removable from the container.
In an additional embodiment of the invention, the pump includes a container and a valve block which has a valve mechanism. An actuator is connected to the valve block and mounted to travel with respect to the valve block. The actuator further selectively actuates the valve mechanism between opened and closed positions. A fluid detector for detecting the level of a pumping fluid is mechanically linked to the actuator. The actuator is arranged to travel a predetermined distance relative to the valve block before the actuator actuates the valve mechanism between the opened and the closed positions.